Microbes. You are what you can’t see you eat.

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This article was originally published by Nexus Media and is republished with permission.

“Microbes make the world go around. Climate change is having a profound impact on them.’’

Microbes are everywhere — on land, in the sea and in the air. They are on us and inside us. All living things interact daily with bacteria, viruses and other microorganisms. We consume them in yogurt, beer and bread. Trillions of them live within our bodies, keeping the human ecosystem in balance. Among other things, they strengthen immunity, control the bad bugs and aid digestion. They also keep the rest of the environment in sync. Scientists call them the “support system” of the biosphere.

“They are so critical to achieving an environmentally sustainable future that ignoring them risks the fate of humanity,” said Rick Cavicchioli, a microbiologist at UNSW Sydney’s school of biotechnology and biomolecular sciences. “Microbes make the world go around — not physically of course — but absolutely in terms of cycling our finite reserve of nutrients on planet Earth. Microbes recycle existing biological matter, regenerate inorganic components and represent the beginning of the food web that feeds all other higher life forms. And climate change is having a profound impact on them.’’

Dozens of microbiologists recently warned that society no longer can afford to overlook microbes when talking about climate change. They called upon scientists, policymakers and individuals globally to include these unseen but essential microorganisms in studies, technology advances, decision-making, and in classroom education. To ignore them is to do so at our own peril, they said.

“To understand how humans and other life forms on Earth — including those we are yet to discover — can withstand anthropogenic climate change, it is vital to incorporate knowledge of the microbial ‘unseen majority,’” they wrote in a statement published in the journal Nature Reviews Microbiology. “We must learn not just how microorganisms affect climate change, including production and consumption of greenhouse gases, but also how they will be affected by climate change and other human activities.”

Paradoxically, microbes are responsible for creating the very fossil fuels that cause global warming by transforming biological matter, a process that takes millions of years. In contrast, “it takes a comparatively miniscule amount of time to burn the fossil fuels and release the carbon back into the atmosphere,” said Cavicchioli, who is leading the international effort to gain recognition for microbes in the climate debate.

Microbes on land and in water are converted to fossil fuels over millions of years, while burning fossil fuels releases greenhouse gases in a small fraction of that time. As a result, the carbon cycle is extremely out of balance. Source: Nature Reviews Microbiology

“This is why burning fossil fuels is so bad,” he added. “The natural carbon cycle on the planet is very much out of balance. Understanding what causes the problems — microbes responding to an ‘out of normal balance’ environment — means we can also correct the problems. We just need the political will.”

Damage caused by the intersection of microbes and climate change already is underway, he added. For example, the melting of permafrost is encouraging microbes to decompose previously frozen animals and plants, which in turn releases greenhouse gases into the atmosphere. This has prompted a dangerous ripple effect within other ecosystems, he said. “By increasing the rate at which greenhouse gases are released, it causes even faster global warming,” he said.

A brown layer of ice algae, an important part of the ocean food web, can be seen on the bottom of Antarctic sea ice. Source: Rick Cavicchioli/Nature Reviews Microbiology

“One consequence of this is the increasing melting of sea ice, [which is] is the ‘home’ of sea ice algae,” he added. “These amazing algae use light energy to grow by removing carbon dioxide from the atmosphere.” This loss causes algae to disappear, meaning less carbon dioxide will be removed from the atmosphere, exacerbating global warming. “This cycle of worsening conditions is called a positive feedback loop, and it is one of the big concerns about anthropogenic climate change — conditions on the planet spiraling out of control,” he said.

“Melting sea ice means ice algae lose their habitat and can no longer harness sunlight energy to fix carbon dioxide, remove it from the atmosphere and generate biomass that feeds all else that we see in the ocean,” he added. “Few people realize that microbes represent about 90 percent of biomass in the oceans. Understanding this will help to be able to reason why microbes have such a big impact — they are small, but there are incredible numbers of them and they perform functions that no other life forms can.”

In addition to soaking up atmospheric CO2, microbes also produce half the oxygen we breathe, and certain microbes also help plants tolerate drought. “By understanding how the microbes keep plants healthy and help them to survive drought conditions will help us make decisions about what the best agricultural practices are,” he said.

But they also live in cows, which produce methane and nitrous oxide, powerful greenhouse gases, when the animals burp and fart. “Because humans want to eat meat and dairy products, many animals are farmed and they contribute very significantly to the atmospheric levels of methane,” he said. “Rice paddies also produce a lot of methane, again as a result of the growth of the microbes.”

Among other things, the experts involved in the campaign are developing materials related to microbes for teachers to use in the classroom. In a March paper in the journal Environmental Microbiology, Cavicchioli and others wrote, “Microbiology literacy needs to become part of the world citizen job description.”

The bottom line: microbes are irreversibly integrated into all living systems. The planet needs them to survive and — in order to do that — the climate discussion must stop excluding them, he said. “Things too big or too small are difficult to relate to,” he said. “We see through human eyes, [but now] we have increasingly improved technologies for studying microbes… So we have a much better chance to learn which microbes are present, what functions they perform, and how they respond to their environment and environmental changes related to human activity, particularly anthropogenic climate change. How will they adapt, that is, evolve? And what will be the consequences of the microbial community changes?”

He encouraged other microbiologists and professional organizations to endorse and sign the consensus statement.

“It is really important that everyone becomes more informed,” Cavicchioli said. We all make decisions about lifestyle and political parties. Those decisions have a big impact on what occurs globally. We need to act on solving the climate crisis. All levels of society, particularly government, business, global support agencies, such as the UN and WHO, need to more effectively incorporate microbes into their thinking. Microbiologists around the world are ready to engage in achieving this.”